In general, many nations are watching the ruling — and China's reaction to it — as a watershed moment for international law.
Most experts who spoke with CNBC said they expected the tribunal to rule against China — although others said that the ruling may have been more limited. But no matter what happened, China repeatedly said it would not abide by the decision. Still, experts said a big legal victory for the Philippines could serve as a bargaining chip against Beijing in any future disputes.
"Big picture: The ruling is going to be critical in the long term, but it doesn't change anything on July 13," Poling said. "China's not going to suddenly roll over and say, 'You got me.' But if you're looking for how to pressure Beijing in the long term, (China will) have it hanging over its head."
While the immediate response from Beijing has been defiance, there could be compromises down the road.
"I see no chance at all that Beijing will soften its stance in the near term, but the power of a decision such as this is in its long-term impact," Dutton said. "Over time, this decision will inevitably be the basis for resolution of the disputes in the South China Sea. Equally inevitable is that a final resolution will be through negotiation between the parties. But I believe there will still be a long road ahead."
About 40 countries, including the United States, have indicated officially that they expect China to abide by the ruling, by Poling's count, so China would presumably lose political capital with those nations if it continued to act in opposition to any tribunal decisions.
Washington, which has a mutual defense treaty with the Philippines and maintains a military presence in the country, recognizes the commercial and strategic importance of the South China Sea itself. But foreign policy experts — and politicians themselves — emphasize that the most critically important element of the dispute is maintaining a rules-based approach to international conflict.
"This is a tremendous source of frustration for the U.S. government: How do we counter what China is doing?" Scobell said, adding that the White House has not come up with "an effective solution" to the South China Sea dispute. President Barack Obama has spoken of a "strong commitment to a regional order where international rules and norms — and the rights of all nations, large and small — are upheld," but Chinese disobedience of the tribunal ruling would disregard those principles.
"This dispute will likely impact the U.S.-China bilateral relationship," Keith said, echoing most other experts interviewed by CNBC.
Dutton said Washington's position would be greatly strengthened if it were to actually ratify the U.N. law of the sea convention. The Senate has refused to sign off on it for years. Only a few other coastal states, including Iran and North Korea, have not approved the measure.